AR15 80% build & trigger issue

[endor]

All,

Very new to the forum and recently attempted my first 80% build, and am having an issue with the trigger. I hope this is the correct forum group to use, and be easy on me.

Here's what was used: Cerro Forge (keyhole marking) 80% lower, 80% Arms Easy Jig + their addon mill/drill bits. All holes were drilled with a drill press.

I'm having an issue with the trigger not resetting properly (hammer follow). Here are the scenarios:

1) Trigger in natural position (not being pulled), hammer cocks normally and consistently, engaging the lower sear with no issues. Pulling the trigger releases the hammer. It seems very smooth.

2) With trigger pulled back and safety selector in the lower, hammer locks onto the disconnector via top sear as it should. When trigger is let go, hammer does not engage the lower (main) sear and hammer swings forward. Not good.

3) With the safety selector out (which gives a bit more up/down movement in the trigger as it's not hitting the selector barrel), and trigger pulled back a little bit more, disconnector engages correct, and when I release the trigger, the hammer will occasionally (maybe half the time) engage with the lower sear as it should. Pulling the trigger again releases the hammer.

I've checked all of the springs, they are in the correct orientation. And yes, I'm running the correct disconnector spring (wide part in the trigger slot). I've also checked the depth of the TCG pocket, and it is well within spec (almost dead-on 1.249", as I used a caliper depth gauge for my final few passes).

The 80% Arms jig was used to drill the two trigger pins, using both sides (not drilling all the way through). They appear to be in spec - I've measured them as best as I could with a caliper.

The company I bought the kit from is sending a new disconnector, but I'm not 100% convinced that's the problem. I'm almost wondering if something else (e.g. sear machining on either the trigger or hammer) is going on.

Thanks for reading my long post... thoughts from the experts?

[SkyHawk]

Another thing to check that you did not mention, be sure the slot for the trigger is not obstructing movement in either direction. Could be that your safety hole is too low, which doesn't explain why it still only works half the time with the selector removed. You may have several issues.

Try the parts in a 100% lower if you have one. The Ruger MSR trigger comes with a dummy lower that also works very well for this.

[bohoki]

there is a front tongue of the disconnector sometimes it has a bur

you can also file the bottom of that tongue to release the hammer a little later in the trigger release

[SkyHawk]

there is a front tongue of the disconnector sometimes it has a bur

you can also file the bottom of that tongue to release the hammer a little later in the trigger release

Yeah good call - I was also thinking the disconnector might not have full travel for some reason, so it is releasing early.

[endor]

Thanks everybody for your help. Wanted to provide an update...

It definitely seemed to be the disconnector. A friend had several other lower part kits, and we swapped disconnectors around and had better luck with other disconnectors. It appears that the top sear ("hook") on my disconnector wasn't "sharp" enough to catch the hammer and hold it under the bottom sear engaged.

The vendor did ship a new disconnector that seemed to be in much beter condition. But.... Since the gun show was this weekend at the OC Fairgrounds, I went ahead and picked up an ALG ACT as I figured an upgraded single stage is probably a better way to go anyhow.

The ALG ACT works perfectly every time and has a much smoother pull anyway.

Thanks again for helping out a newbie....